1. Field of the Invention.
This invention relates to improved jet fuels. More particularly, this invention relates to compositions of matter comprising a mixture of a jet fuel and an aluminum di-acid soap of a saturated carboxylic acid having from 8 to 20 carbon atoms.
2. Description of the Prior Art.
When an airplane crashes or is forced to crash land or subjected to various other impulsive mishaps, its fuel tanks are often punctured or ruptured. When this happens, fuel from within the tanks spread into the atmosphere. Much of the fuel is in the form of a fine spray or mist. The tiny mist droplets are, because of their extremely large surface area, easily ignitable. If ignition occurs, a large, spreading fireball results.
It would be advantageous if the fuel were such that fine mist droplets were prevented from forming in the case of a fuel tank puncture or rupture mishap. That is, it would be advantageous if the viscosity were such that the fuel spread was minimized and, should aspiration occur, relatively large drops rather than small mist droplets would form.
In the past, various materials have been added to jet fuels to increase viscosities. Polyisobutylene, polyisoprene, copolymers of ethylene acetate and vinyl acetate and various acrylic polymers and copolymers have been experimented with as demisting agents. These materials have been added to the fuel in amounts varying from 0.1 to 3 percent of the total weight of the composition.
The prior art materials have had certain disadvantages associated with them. First, their demisting properties, i.e., their ability to make the viscosity of the fuel such that fine mists do not form when mishaps occur, have been detrimental to ignition and combustion properties in engines. When the "demisted" fuel is injected into an engine for burning, the fuel is in the form of large drops. This makes ignition in the engine difficult. Ignition is particularly difficult during cold starts and after flameouts. Second, the previously tested materials tend to degrade when subjected to shear forces when the fuel is pumped. Single bond rupture of these very high molecular weight polymer chains causes very sharp reductions in the viscosity causing the fuel to lose its demisted quality. Third, occasions arise in maintenance of aircraft, when it is desirable to remove the fuel from the tanks. Fuels thickened with state of the art polymeric thickeners are difficult to remove and completely drain from the aircraft (about 10% of the fuel remains as hold up).